CN112413176A - Rotary valve mechanism and cryogenic refrigerator - Google Patents

Abstract

The invention discloses a rotary valve mechanism and a cryogenic refrigerator, wherein the rotary valve mechanism comprises: the gas distribution valve (6) and the rotary valve (7) are coaxially arranged in the cover body (2) of the low-temperature refrigerator, and a jack (74) for inserting the eccentric cam handle (31) is arranged on the back surface (75) of the rotary valve (7) relative to a switching surface (73) on the rotary valve (7); an elastic body (100) is installed in a gap between the cam shank (31) and the insertion hole (74), and the elastic body (100) is installed in a compressed manner along the central axial direction of the cam shank (31). The invention provides eccentric pretightening force by compressing and deforming the elastic body between the cam handle and the jack into a switching surface at one side of the high-pressure groove of the rotary valve, reduces the influence of asymmetrical pressure in the whole period and reduces the leakage risk of refrigerant gas in the area.

Description

Rotary valve mechanism and cryogenic refrigerator

Technical Field

The invention relates to the technical field of cryogenic refrigerators, in particular to a rotary valve mechanism and a cryogenic refrigerator.

Background

A cryogenic refrigerator, typified by a Gifford-McMahon (GM) refrigerator, has an expander and a compressor of a working gas (also referred to as a refrigerant gas). The refrigerator provides high pressure air flow exhausted from the compressor, and the high pressure air flow enters the pushing piston arranged in the cylinder via the air distributing valve and the rotary valve, exchanges heat with the cold storage material, then does work expansion in the expansion cavity, flows out of the air distributing mechanism via the pushing piston and returns to the low pressure cavity of the compressor. Through the continuous circulation process, the refrigeration effect is formed.

One of the rotary valve and the gas distribution valve is made of resin wear-resistant material, and the other is made of metal material. During operation, two component planes are mutually attached, and the communication states of the channels on the rotary valve and the gas distribution valve are switched through the rotation of the rotary valve, so that the switching of high-pressure and low-pressure gas flows is realized. The process of laminating compresses tightly in time through the pressure differential of valve train both sides. For the GM refrigerator, the high pressure groove and the low pressure hole on the rotary valve are in gas tight communication with the high pressure gas stream and the low pressure gas stream, respectively, and are eccentrically disposed on both sides of the axis of rotation of the rotary valve itself. The pressure between the switching surface and the valve face in one period is 'asymmetric pressure', namely, the pressure on two sides symmetrical by the rotating shaft is not the same. Such valves are therefore referred to as asymmetric flat rotary valves.

The high-pressure air discharged from the compressor acts on the back surface of the air distribution valve, and the air distribution valve is tightly attached to the rotary valve by the positive pressure on the back surface and the elastic force of the spring to form an airtight sliding contact surface, so that the switching surface of the asymmetric rotary valve and the air distribution valve surface of the air distribution valve are not pushed open by the air pressure (a region on the sliding surface to which the pressures of both sides are applied is referred to as a both-side acting region). However, in a configuration in which the working high-pressure gas and the spring press the back surface of the distribution valve (the opposite distribution valve surface) symmetrically with respect to the central axis, the "asymmetric pressure" generates a torque in the double acting regions, which makes the double acting regions closer to the rotary valve high-pressure groove side more likely to be separated, and there is a risk of refrigerant gas leakage.

Prior art 1 proposes an improvement in that a spring is eccentrically installed on a side close to a gas distribution hole on a gas distribution valve so that the center of the relief force of the spring is closer to the gas flow path side. This technique is mainly directed to the time period (zone period) where the leakage probability is the greatest in the double-acting zone, but during the remaining time period, the "asymmetric pressure" still exists, i.e., the leakage problem still exists.

In the prior art 2, the structure of the air distribution valve is improved, and in the state that high-pressure air inlet is communicated with the air distribution hole, the two action areas are subjected to larger positive pressure, but when the low-pressure exhaust process is communicated with the air distribution hole, the positive pressure of the two action areas is reduced, and the 'asymmetric pressure' still exists, so that the leakage risk still exists.

Disclosure of Invention

The present invention provides a rotary valve mechanism and a cryocooler to reduce the risk of refrigerant gas leakage.

In order to solve the above-mentioned technical problem, the present invention provides a rotary valve mechanism comprising: the gas distribution valve and the rotary valve are coaxially arranged in a cover body of the low-temperature refrigerator, and are characterized in that a jack for inserting an eccentric cam handle is arranged on the back surface of the rotary valve relative to a switching surface on the rotary valve; an elastic body is arranged in a gap between the cam shank and the jack and is arranged in a compressed mode along the central axial direction of the cam shank.

Furthermore, the air distribution valve is limited by a valve body positioning pin to rotate around the axis, and the rotary valve is arranged on a bearing and is coaxially pressed on the air distribution valve along the axis of the air distribution valve in a front-pressing manner.

Further, a high-pressure air hole on the air distribution valve hermetically communicates the high-pressure air flow discharged from the compressor with a high-pressure groove extending in a radial direction on the rotary valve on a center side corresponding to the rotary shaft.

Further, the low-pressure hole on the other side of the rotary valve with respect to the high-pressure groove in the radial direction is in airtight communication with the low-pressure passage in the housing.

Further, the elastic body is a spring or a washer.

Further, the elastic body is an O-ring or a non-metal pad.

The invention also provides a low-temperature refrigerator comprising the rotary valve mechanism.

Furthermore, the air distribution valve is eccentrically fixed on the cover body through a valve body positioning pin, a spring is embedded at the end side departing from the air distribution valve, and the rotary valve is positioned in the cover body through a bearing.

The embodiment of the invention has the beneficial effects that: the rotary valve is processed almost the same as the traditional process, only the elastomer with low price is added, the elastomer is compressed and deformed between the cam handle and the jack to form a switching surface at one side of a high-pressure groove of the rotary valve, eccentric pretightening force is provided, the influence of asymmetrical pressure is reduced in the whole period, and the risk of refrigerant gas leakage in the area is reduced.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

Fig. 1 is a schematic three-dimensional exploded view of a rotary valve mechanism according to a first embodiment of the present invention.

FIG. 2 is a schematic view of the cryocooler of the present invention.

FIG. 3 is a schematic plan view of a rotary valve mechanism in two states according to an embodiment of the present invention.

Fig. 4 is a schematic diagram showing the change of the pressure and the volume of the refrigeration cycle in the expansion chamber of the refrigerator according to the present embodiment.

The reference signs are: 1-a compressor; 1 a-a high pressure exhaust duct; 1 b-a low pressure suction duct; 2, a cover body; 21-cover body air hole; 22 — a low pressure path; 3, a cam; 31-eccentric cam handle; 4, a guide sleeve; 5, connecting rods; 6-distributing valve; 61-gas distribution valve face; 62-high pressure vent; 63-air hole of air distribution valve; 7-a rotary valve; 71-low pressure hole; 72-high pressure tank; 73 — switching plane; 74-a jack; 75 — back; 8-a thermal chamber; 9-an expansion chamber; 10 a-front hole of piston; 10 b-piston rear bore; 10 c-cold storage material; 12-a motor; 13-a cylinder; 14-a bearing; 15-a spring; 16-valve body locating pin; 100-pre-tightening force mechanism.

Detailed Description

The following description of the embodiments refers to the accompanying drawings, which are included to illustrate specific embodiments in which the invention may be practiced. The terms of direction and position of the present invention, such as "up", "down", "front", "back", "left", "right", "inside", "outside", "top", "bottom", "side", etc., refer to the direction and position of the attached drawings. Accordingly, the use of directional and positional terms is intended to illustrate and understand the present invention and is not intended to limit the scope of the present invention.

Referring to fig. 1, a rotary valve mechanism according to an embodiment of the present invention includes: a gas distribution valve 6 and a rotary valve 7 coaxially installed in a cover body 2 of a cryogenic refrigerator, wherein a back surface 75 of the rotary valve 7 is provided with a plug hole 74 for inserting an eccentric cam shank 31 with respect to a switching surface 73 on the rotary valve 7; an elastic body 100 is mounted in a gap between the cam shank 31 and the insertion hole 74, and the elastic body 100 is mounted in a compressed manner along the central axial direction of the cam shank 31.

Specifically, referring to fig. 2 to 3, in the present embodiment, the cryocooler includes a compressor 1, a cover 2, a cylinder 13, and a pushing piston 10, wherein a motor 12 and a driving cam 3 are installed in the cover 2; the eccentric cam handle 31 on the cam 3 drives the connecting rod 5 to convert the rotary motion into the up-and-down reciprocating motion, thereby driving the pushing piston to move up and down in the cylinder 13. The air distribution mechanism RV consists of an air distribution valve 6 and a rotary valve 7. The gas distribution valve 6 is mounted in the housing 2, fixed therein by a positioning pin 16, and arranged coaxially with the rotary valve 7. The cam shank 31 rotates the rotary valve 7 mounted on the bearing 14 along the rotation axis. The compressor 1 sucks and compresses a refrigerant gas to discharge the refrigerant gas as a high-pressure refrigerant gas. The high-pressure discharge pipe 1a supplies the high-pressure refrigerant gas to the cover 2, and the high-pressure refrigerant gas is transferred to the high-pressure groove 72 of the rotary valve 7, which is hermetically bonded to the high-pressure gas through the high-pressure gas hole 62 on the center axis of the gas distribution valve 6, and the high-pressure groove 72 is not communicated with the low-pressure hole 71. The rotary valve 7 is provided with a low pressure hole 71, and the low pressure hole 71 is communicated with the low pressure passage 22 in the cover body 2. The high pressure groove 72 extends radially outward along the rotation axis O, and is eccentrically disposed on the rotation shaft 7. The low pressure hole 71 is disposed opposite the high pressure groove 72 on the other side of the axis O.

According to the position shown in fig. 2, the low-pressure hole 71 is in overlapped communication with the air distribution valve air hole 63 on the air distribution valve 6; at this moment, the low pressure hole 71 on the rotary valve 7, the gas distribution valve air hole 63 on the gas distribution valve 6 and the cover body air hole 21 on the cover body 2 are communicated, the system is in a low pressure exhaust stage, gas in the expansion cavity 9 is changed from high pressure to low pressure, and flows out through the piston rear hole 10b, the cold storage material 10c and the piston front hole 10a on the push piston in sequence and returns to the low pressure air suction pipeline 1b of the compressor 1. When the rotary valve 7 rotates a certain angle, the low pressure hole 71 is not communicated with the air distribution valve air hole 63 on the air distribution valve 6, and becomes a high pressure groove 72 on the rotary valve 7 to be communicated with the air distribution valve air hole 63 on the air distribution valve 6 (the matching relation is not shown), at this moment, the high pressure gas discharged by the compressor 1 enters the cylinder 13 through the high pressure air hole 62 on the air distribution valve 6 and the high pressure groove 72 on the rotary valve 7 communicated with the air distribution valve, and enters the expansion chamber 9 through the piston front hole 10a on the push piston, the cold storage material 10c and the piston rear hole 10b in sequence. In the above process, the high pressure gas discharged from the compressor 1 acts on the rear surface of the distribution valve 6, and the distribution valve 6 is tightly attached to the rotary valve 7 by the positive pressure on the rear surface and the elastic force of the spring 15 to form an airtight sliding contact surface. The rotary valve 7 and the gas distributing valve 6 are both designed as a revolving body structure along the rotation axis, wherein the rotary valve 7 is rotatably supported by a bearing 14 and is arranged in the cover body 2; the gas distribution valve 6 is disposed coaxially with the rotary valve 7 in the cover body 2, and the gas distribution valve 6 is fixed by a valve body positioning pin 16 so as not to be rotatable but detachable in the axial direction of the center axis O.

The air distribution valve 6 and the rotary valve 7 are coaxially and oppositely arranged in the refrigerator cover body 2 around an axis O (dotted line), the switching surface 73 of the rotary valve 7 is attached to the air distribution valve surface 61 of the air distribution valve in the forward direction, and the high-pressure air on the back surface of the air distribution valve 6 departing from the air distribution valve surface 61 and the spring 15 arranged at the center end are used for forward pressing. The switching surface 73 of the rotary valve 7 is formed with a high-pressure groove 72, generally in a "kidney shape", extending radially outward from the center axis O of rotation of the rotary valve 7. The high pressure groove 72 does not penetrate the body of the rotary valve 7 and does not communicate with the receptacle 74. The low-pressure hole 71 is formed in a "fan ring" shape along a fixed radius at a position facing the rotation axis O with respect to the high-pressure groove 72, penetrates the rotary valve 7, and communicates with the low-pressure passage 22 in the cover body 2. When the rotary valve 7 rotates along its own rotation axis O, the high pressure groove 72 and the low pressure hole 71 are in airtight communication with the air distribution hole 63 at an interval, forming a valve switching pattern.

The rotary valve 7 has a receptacle 74 in a back surface 75 thereof into which the eccentric cam lever 31 is inserted and is rotated about the rotational axis O by the motor 12. The central line of the cam shank 31 is coincident with the central line of the insertion hole 74, and the circular motion of the cam shank 31 can be converted into the up-and-down linear reciprocating motion of the piston 10 through the conversion of the connecting rod 5.

It should be noted that, in the present embodiment, the terms "upper" and "lower" refer to the orientation of the rotary shaft O of the rotary valve 7 or the central axis O of the gas distribution valve 6. It will be appreciated that the axis of rotation O of the rotary valve 7 is coaxial with the central axis O of the gas distribution valve 6.

The high pressure gas port 62 of the gas distribution valve 6 of the rotary valve mechanism of the present invention is generally a through hole disposed about the central axis O, and the gas distribution valve gas port 63 is disposed "below" the central axis O near the side of the thermal chamber 8 and in gas-tight communication with the gas port 21 of the housing 2.

In order for the cryogenic refrigerator to be able to produce a cooling effect, the volume change and the pressure change inside the expansion chamber 9 must be according to the cyclic manner described in fig. 4, i.e. clockwise. The b → c process indicates that the low pressure valve is open and the low pressure exhaust process is taking place, the volume of expansion 9 is now at its maximum, and the piston 10 is at the uppermost position of the reciprocating stroke, as shown in the left drawing of fig. 3, with the cam shaft 31 "above" the axis of rotation O. Since the gas distribution hole 63 of the gas distribution valve 6 is arranged "below" the central axis O, i.e. near the side of the hot chamber 8, the high pressure groove 72 of the rotary valve 7 is now not in communication with the gas distribution hole 63, and the radial extension direction of the high pressure groove 72 must be "above" the rotation axis O, otherwise the high pressure gas flow will be conducted. At this time, the insertion hole 74 is located "above" the rotation axis O together with the high-pressure groove 72. Similarly, the d → a process indicates that the high pressure valve is open and the high pressure intake process is taking place, the volume of expansion 9 now being at its minimum, and the piston 10 being at the lowest position of the reciprocating stroke, as shown in the right drawing of fig. 3, with the cam shaft 31 "below" the axis of rotation O. The high pressure grooves 72 in the rotary valve 7 must now communicate with the gas distribution openings 63, and the high pressure grooves 72 must extend radially "below" the axis of rotation O, otherwise the low pressure gas flow will be conducted. At this time, the insertion hole 74 is located "below" the high-pressure groove 72 with respect to the rotation axis O.

Further explaining the structural embodiment of the rotary valve mechanism, the insertion hole 74 is always located on the same side of the rotary shaft O as the radial extension direction of the high pressure groove 72 of the rotary valve 7. An elastic body 100 is installed in the gap between the cam shank 31 and the insertion hole 74. The elastic body 100 is installed in a compressed state along the central axis (dotted line) direction of the cam shank 31.

The elastic body 100 is pressed by the cam shank 31, and the generated pre-tightening force acts on the bottom of the insertion hole 74. Since the insertion hole 74 is arranged eccentrically with respect to the rotational axis O and on the rear side 75 on the side corresponding to the radial extension direction of the high-pressure groove 72, this biasing force presses the switching surface 73 of the rotary valve 7 from the front side against the valve face 61 of the valve 6, and the switching surface 73 is more easily pressed against the valve face 61 on the side of the radial extension direction of the high-pressure groove 72. This has the opposite effect of the force created by the high pressure gas flow in the high pressure groove 72, i.e., the aforementioned "asymmetric pressure".

The elastic body 100 is selected from a member having a compression characteristic along the central axis of the cam shank 31, such as a spring, a washer, an O-ring, a rubber pad, etc., and is not limited to the above-mentioned types of members. Further, the elastic body 100 is not limited to a material, and may be a metal, a plastic, a rubber, or the like as long as it has a compression characteristic in a predetermined direction, for example, a tension clip having a "V" shape or a "U" shape in cross section.

Compared with the method that the cam handle 31 is directly rigidly acted on the jack 74, the pretightening force generated by the elastomer 100 in a compressed mode can be adaptively changed according to the change of the asymmetrical pressure in one period, namely, the pretightening force is larger to inhibit the leakage of the valve according to the maximum pressure area, and in the invention, the compressible elastomer 100 is only added between the cam handle 31 and the jack 74, and the asymmetrical pressure of the rotary valve 7 acting on the valve face 61 of the gas distribution valve is counteracted by the pretightening force of the compression deformation of the elastomer, so that the risks of separation and gas leakage of the two acting areas are reduced.

Corresponding to the rotary valve mechanism in the first embodiment of the invention, the second embodiment of the invention provides a cryogenic refrigerator, which comprises the rotary valve mechanism.

Furthermore, the gas distribution valve 6 is eccentrically fixed on the housing 2 by a valve body positioning pin 16, a spring 15 is embedded on the end side facing away from the gas distribution valve 6, and the rotary valve 7 is positioned in the housing 2 by a bearing 14. The low-temperature refrigerator is any type of valve-switching refrigerator, and is not limited to gifford-mcmahon refrigerators, solvin refrigerators, pulse tube refrigerators, and the like.

As can be seen from the above description, the embodiments of the present invention have the following beneficial effects: the rotary valve is processed almost the same as the traditional process, only the elastomer with low price is added, the elastomer is compressed and deformed between the cam handle and the jack to form a switching surface at one side of a high-pressure groove of the rotary valve, eccentric pretightening force is provided, the influence of asymmetrical pressure is reduced in the whole period, and the risk of refrigerant gas leakage in the area is reduced.

The above disclosure is only for the purpose of illustrating the preferred embodiments of the present invention, and it is therefore to be understood that the invention is not limited by the scope of the appended claims.

Claims (8)

1. A rotary valve mechanism comprising: the gas distribution valve (6) and the rotary valve (7) are coaxially arranged in a cover body (2) of the low-temperature refrigerator, and the gas distribution valve is characterized in that a jack (74) for inserting the eccentric cam handle (31) is arranged on the back surface (75) of the rotary valve (7) relative to a switching surface (73) on the rotary valve (7); an elastic body (100) is installed in a gap between the cam shank (31) and the insertion hole (74), and the elastic body (100) is installed in a compressed manner along the central axial direction of the cam shank (31).

2. A rotary valve mechanism according to claim 1, wherein the distribution valve (6) is restricted in its rotational movement about its axis by a valve body positioning pin (16), and the rotary valve (7) is mounted on bearings (14) coaxially with the axis of the distribution valve (6) and pressed frontally against the distribution valve (6).

3. A rotary valve mechanism according to claim 1, wherein the high pressure gas port (62) in the gas distribution valve (6) is adapted to gas-tightly communicate the high pressure gas flow discharged from the compressor (1) with the high pressure groove (72) in the rotary valve (7) having a radial extension on the center side corresponding to the axis of rotation.

4. A rotary valve mechanism as claimed in claim 3, characterized in that the low-pressure port (71) at the other side of the rotary valve (7) in the radial direction with respect to the high-pressure groove (72) is in gas-tight communication with the low-pressure passage (22) in the housing (2).

5. A rotary valve mechanism as claimed in claim 1 wherein the elastomer (100) is a spring or a washer.

6. A rotary valve mechanism as claimed in claim 1 wherein the elastomer (100) is an O-ring or a non-metallic pad.

7. A cryocooler comprising a rotary valve mechanism according to any one of claims 1 to 6.

8. Cryocooler according to claim 7, characterized in that the gas distribution valve (6) is eccentrically fixed to the housing (2) by means of a valve body positioning pin (16), a spring (15) being embedded on the end side facing away from the gas distribution valve (6), and the rotary valve (7) being positioned in the housing (2) by means of a bearing (14).

Images